Lv50 Rogue quest "A Simple Request" does not chain into pt 4

Hello everyone. I'm level 50 and I encountered a chain bug in Nost. I was doing this quest: http://www.wowwiki.com/Quest:A_Simple_Request and when I turned in "Encoded Fragments", I couldn't pick up the final chain called "The Azure Key". Is this a known bug? I read I had to be at least level 50 to pick it up. Any information would be great, thanks.